Abstract: An air lift diffuser assembly is made up of an air lift tube and a fixed, non-rotating bubble-emitting diffuser horizontally spaced beneath an open end of the air lift tube, the air lift tube and diffuser being releasably positioned in centered relation to a casing which is submerged beneath a body of water and is dimensioned such that the annular space between the air lift tube and casing has a greater cross-sectional area than the cross-sectional area across the tube, and an air supply pipe extends downwardly through the annular space into communication with the diffuser whereby to direct air under pressure into the diffuser which discharges the air in the form of fine bubbles upwardly through the air lift tube where the bubbles become intimately mixed with the water and dispersed in the form of dissolved oxygen over a substantial area of the body of water above the assembly.

Abstract: An air lift diffuser for use in the aeration of a body of water including an air lift tube and a gas diffuser located a distance below the open bottom end of the air lift tube. The distance in question is sufficiently large that there is substantially no obstruction to the passage of water from the space surrounding the air lift diffuser into the space between the air lift tube and the diffuser, but at the same time is not so large that rising air bubbles are likely to escape and flow outside the air lift tube. In one embodiment, a cylindrical return tube is provided around the air lift tube that directs the water stream and gas bubbles entrained therein downward, after they have risen in the air lift tube, so as to return the aerated water to the lower levels of the body of water being aerated.

Abstract: A fluid diffuser for dispersing gas bubbles or liquid droplets into a body of receiving liquid in a tank. The diffuser includes a fluid-emitting member for communication with the body of receiving liquid, which member defines a fluid plenum. A portion of at least one of the walls of the fluid-emitting member is porous and has a foraminous outer surface, to permit the passage of fluid from the plenum into the body of liquid. A slot-forming chamber has a wall that defines a narrow, elongated slot extending parallel to the foraminous outer surface of the plenum-defining wall of the fluid-emitting member, with the foraminous outer surface lying primarily outside the slot. Fluid supplied under pressure to the plenum flows out through the porous wall portion to produce small nascent fluid spheroids on the foraminous surface of that portion.

Abstract: A diffuser for dispersing gas into a body of liquid that may contain suspended solids. Under ordinary clogging conditions, the diffuser will remain operative over an indefinite period of time by reason of large gas outlet openings at the bottom of the gas plenum chamber. In addition, it can be employed for a good portion of that time to disperse a substantial flow of coarse bubbles and fine bubbles, in a desired combination, simultaneously from a single gas plenum. Careful selection of the permeability and area of a top porous wall of a gas plenum chamber, together with proper selection of the level, size and number of coarse bubble gas outlet openings in the side walls of the plenum chamber, achieve the second feature.